/*
  motion_control.c - high level interface for issuing motion commands
  Part of Grbl

  Copyright (c) 2009-2011 Simen Svale Skogsrud
  Copyright (c) 2011 Sungeun K. Jeon
  
  Grbl is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.

  Grbl is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with Grbl.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "Marlin.h"
#include "stepper.h"
#include "planner.h"

// The arc is approximated by generating a huge number of tiny, linear segments. The length of each 
// segment is configured in settings.mm_per_arc_segment.  
// void mc_arc(float *position, float *target, float *offset, uint8_t axis_0, uint8_t axis_1, 
//   uint8_t axis_linear, float feed_rate, float radius, uint8_t isclockwise, uint8_t extruder)
// {      
//   //   int acceleration_manager_was_enabled = plan_is_acceleration_manager_enabled();
//   //   plan_set_acceleration_manager_enabled(false); // disable acceleration management for the duration of the arc
//   float center_axis0 = position[axis_0] + offset[axis_0];
//   float center_axis1 = position[axis_1] + offset[axis_1];
//   float linear_travel = target[axis_linear] - position[axis_linear];
//   float extruder_travel = target[E_AXIS] - position[E_AXIS];
//   float r_axis0 = -offset[axis_0];  // Radius vector from center to current location
//   float r_axis1 = -offset[axis_1];
//   float rt_axis0 = target[axis_0] - center_axis0;
//   float rt_axis1 = target[axis_1] - center_axis1;
  
//   // CCW angle between position and target from circle center. Only one atan2() trig computation required.
//   float angular_travel = atan2(r_axis0*rt_axis1-r_axis1*rt_axis0, r_axis0*rt_axis0+r_axis1*rt_axis1);
//   if (angular_travel < 0) { angular_travel += 2*M_PI; }
//   if (isclockwise) { angular_travel -= 2*M_PI; }
  
//   //20141002:full circle for G03 did not work, e.g. G03 X80 Y80 I20 J0 F2000 is giving an Angle of zero so head is not moving
//   //to compensate when start pos = target pos && angle is zero -> angle = 2Pi
//   if (position[axis_0] == target[axis_0] && position[axis_1] == target[axis_1] && angular_travel == 0)
//   {
// 	  angular_travel += 2*M_PI;
//   }
//   //end fix G03
  
//   SERIAL_ECHOPGM("angular_travel="); SERIAL_ECHOLN(angular_travel);
//   SERIAL_ECHOPGM("radius="); SERIAL_ECHOLN(radius);
//   SERIAL_ECHOPGM("center_axis0="); SERIAL_ECHOLN(center_axis0);
//   SERIAL_ECHOPGM("center_axis1="); SERIAL_ECHOLN(center_axis1);
//   SERIAL_ECHOPGM("target X "); SERIAL_ECHOLN(target[X_AXIS]);
//   SERIAL_ECHOPGM("target Y "); SERIAL_ECHOLN(target[Y_AXIS]);
//   SERIAL_ECHOPGM("target Z "); SERIAL_ECHOLN(target[Z_AXIS]);

//   float millimeters_of_travel = hypot(angular_travel*radius, fabs(linear_travel));
//   SERIAL_ECHOPGM("millimeters_of_travel="); SERIAL_ECHOLN(millimeters_of_travel);
//   if (millimeters_of_travel < 0.001) { return; }
//   uint16_t segments = floor(millimeters_of_travel/MM_PER_ARC_SEGMENT);
//   if(segments == 0) segments = 1;
  
//   /*  
//     // Multiply inverse feed_rate to compensate for the fact that this movement is approximated
//     // by a number of discrete segments. The inverse feed_rate should be correct for the sum of 
//     // all segments.
//     if (invert_feed_rate) { feed_rate *= segments; }
//   */
//   float theta_per_segment = angular_travel/segments;
//   float linear_per_segment = linear_travel/segments;
//   float extruder_per_segment = extruder_travel/segments;
  
//   /* Vector rotation by transformation matrix: r is the original vector, r_T is the rotated vector,
//      and phi is the angle of rotation. Based on the solution approach by Jens Geisler.
//          r_T = [cos(phi) -sin(phi);
//                 sin(phi)  cos(phi] * r ;
     
//      For arc generation, the center of the circle is the axis of rotation and the radius vector is 
//      defined from the circle center to the initial position. Each line segment is formed by successive
//      vector rotations. This requires only two cos() and sin() computations to form the rotation
//      matrix for the duration of the entire arc. Error may accumulate from numerical round-off, since
//      all double numbers are single precision on the Arduino. (True double precision will not have
//      round off issues for CNC applications.) Single precision error can accumulate to be greater than
//      tool precision in some cases. Therefore, arc path correction is implemented. 

//      Small angle approximation may be used to reduce computation overhead further. This approximation
//      holds for everything, but very small circles and large mm_per_arc_segment values. In other words,
//      theta_per_segment would need to be greater than 0.1 rad and N_ARC_CORRECTION would need to be large
//      to cause an appreciable drift error. N_ARC_CORRECTION~=25 is more than small enough to correct for 
//      numerical drift error. N_ARC_CORRECTION may be on the order a hundred(s) before error becomes an
//      issue for CNC machines with the single precision Arduino calculations.
     
//      This approximation also allows mc_arc to immediately insert a line segment into the planner 
//      without the initial overhead of computing cos() or sin(). By the time the arc needs to be applied
//      a correction, the planner should have caught up to the lag caused by the initial mc_arc overhead. 
//      This is important when there are successive arc motions. 
//   */
//   // Vector rotation matrix values
//   float cos_T = 1-0.5*theta_per_segment*theta_per_segment; // Small angle approximation
//   float sin_T = theta_per_segment;
  
//   float arc_target[4];
//   float sin_Ti;
//   float cos_Ti;
//   float r_axisi;
//   uint16_t i;
//   int8_t count = 0;

//   // Initialize the linear axis
//   arc_target[axis_linear] = position[axis_linear];
  
//   // Initialize the extruder axis
//   arc_target[E_AXIS] = position[E_AXIS];

//   for (i = 1; i<segments; i++) { // Increment (segments-1)
    
//     if (count < N_ARC_CORRECTION) {
//       // Apply vector rotation matrix 
//       r_axisi = r_axis0*sin_T + r_axis1*cos_T;
//       r_axis0 = r_axis0*cos_T - r_axis1*sin_T;
//       r_axis1 = r_axisi;
//       count++;
//     } else {
//       // Arc correction to radius vector. Computed only every N_ARC_CORRECTION increments.
//       // Compute exact location by applying transformation matrix from initial radius vector(=-offset).
//       cos_Ti = cos(i*theta_per_segment);
//       sin_Ti = sin(i*theta_per_segment);
//       r_axis0 = -offset[axis_0]*cos_Ti + offset[axis_1]*sin_Ti;
//       r_axis1 = -offset[axis_0]*sin_Ti - offset[axis_1]*cos_Ti;
//       count = 0;
//     }

//     // Update arc_target location
//     arc_target[axis_0] = center_axis0 + r_axis0;
//     arc_target[axis_1] = center_axis1 + r_axis1;
//     arc_target[axis_linear] += linear_per_segment;
//     arc_target[E_AXIS] += extruder_per_segment;

//     SERIAL_ECHOPGM("arc_target 1="); SERIAL_ECHOLN(arc_target[axis_0]);
//     SERIAL_ECHOPGM("arc_target 2="); SERIAL_ECHOLN(arc_target[axis_1]);
//     SERIAL_ECHOPGM("arc_target 3="); SERIAL_ECHOLN(arc_target[axis_linear]);

//     calculate_delta(arc_target);

//     clamp_to_software_endstops(arc_target);
//     plan_buffer_line(arc_target[X_AXIS], arc_target[Y_AXIS], arc_target[Z_AXIS], arc_target[E_AXIS], feed_rate, extruder);
    
//   }
//   // Ensure last segment arrives at target location.
//   plan_buffer_line(target[X_AXIS], target[Y_AXIS], target[Z_AXIS], target[E_AXIS], feed_rate, extruder);

//   //   plan_set_acceleration_manager_enabled(acceleration_manager_was_enabled);
// }
